chore: always compare enums with ==

[adangel]

Describe the PR

Ran #6193 against current PMD source code. Used the following snippet in build-tools pmd-dogfood-config.xml:

    <!-- https://github.com/pmd/pmd/issues/6193 -->
    <rule name="UnnecessaryEqualsForEnum"
          language="java"
          since="36"
          message="Use == to compare enum values"
          class="net.sourceforge.pmd.lang.rule.xpath.XPathRule">
        <description>Enum should be compared using ==, this is more readable. Using equals() is not necessary (and is prone to NPE).</description>
        <priority>1</priority>
        <properties>
            <property name="xpath">
                <value><![CDATA[
//MethodCall[pmd-java:matchesSig("_#equals(java.lang.Object)")]
  [*[pmd-java:typeIs("java.lang.Enum")] or
   ArgumentList[*[pmd-java:typeIs("java.lang.Enum")]]]
]]></value>
            </property>
        </properties>
    </rule>

Related issues

• Refs [java] New Rule: Always compare enum values with == #6193

Ready?

• Added unit tests for fixed bug/feature
• Passing all unit tests
• Complete build ./mvnw clean verify passes (checked automatically by github actions)
• Added (in-code) documentation (if needed)

[pmd-actions-helper]

Documentation Preview

Compared to main:
This changeset changes 0 violations,
introduces 0 new violations, 0 new errors and 0 new configuration errors,
removes 0 violations, 25 errors and 8 configuration errors.

Regression Tester Report

(comment created at 2025-11-06 15:06:42+00:00 for 6b6c555)

[adangel]

I'm going to merge this for 7.19.0, assuming this is ok.